#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main() {
	int m = 0;
	int n = 0;
	float p = 0;
	scanf("%d", &m);
	while (n < m) {
		p += 1 / (n + 5);
		n++;
	}

    printf("%f", p);
	return 0;
}